A feeding trial was conducted to evaluate the effect of herbs as feed additive on rumen fermentation patterns and haemato-biochemical parameters in Marwari rams fed wheat straw based complete feed. Twenty Marwari rams of same breed age group (15-18 months) and of uniform conformation were randomly distributed into 5 groups of 4 animals in each subjected to five treatments. The dietary treatments were group-T1 fed complete feed without any herb (control), T2 fed complete feed with 4% Shatavari (Asparagus racemosus), T3 fed complete feed with 3% Brahmi (Bacopa monnieri), T4 fed complete feed with 3% Bhringraj (Eclipta alba) and T5 fed complete feed with 3% Jiwanti (Leptadenia reticulata). At the end of metabolic trial rumen liquor sample were collected from each animal at 0, 2, 4, 6, 8, 12 and 18 h post feeding for the estimation of pH, total volatile fatty acid, total protozoal count and various nitrogen fractions such as total nitrogen, ammonia nitrogen, TCA-precipitable nitrogen and non-protein nitrogen. Besides this, haemato-biochemical parameters were also estimated at the end of trial to study the physiological status of health of experimental rams. The results from this study showed highly significant (P<0.01) effect of period on pH, TVFA, total protozoal count, ammonia nitrogen, total nitrogen, TCA-precipitable nitrogen and non-protein nitrogen. Herb supplementation also significantly (P<0.01) improved the rumen fermentation resulting in increased TVFA, decreased total protozoal count and ammonia nitrogen, increased total nitrogen and TCA-precipitable nitrogen. Whereas, non-significant effect of treatment was observed on pH, NPN and various haemato-biochemical parameters. It was concluded that supplementation of Shatavari, Brahmi, Bhringraj and Jiwanti herbs as feed additives could be a viable proposition for better utilization of nutrients through improvement in rumen fermentation in the Marwari rams.